The parietal eye of lizard is a photosensitive organ located on the dorsal midline of the animal's head. Its photoreceptors synapse directly onto ganglion cells, though a class of interneurons may be present. Afferent signal flow is modified by centrifugal input. It is proposed to characterize the morphological types of photoreceptors and neurons using conventional light and electron microscopy of Golgi-impregnated tissue. The connectivity of the neurons will be investigated. Electrophysiological techniques will be employed to characterize the responses to light of the various classes of cells in the parietal eye. Further investigation of the central projections of the ganglion cells will be pursued.